The invention relates to a semiconductor x-ray detector with means for converting the x-rays into light and with a semiconductor assembly as optical-electrical converter.
A known semiconductor x-ray detector of this type consists of a semiconductor diode and a fluorescent layer overlying the diode and exposed to x-radiation at one lateral surface so as to convert the impinging radiation into visible light. The visible light is transmitted to the semiconductor diode at the opposite lateral side of the fluorescent layer for conversion into an electrical signal. With the use of polycrystalline fluorescent substances the absorption length for x-radiation is generally far greater than for light so that the quanta efficiency degree is low. It cannot even be substantially increased through enlargement of the thickness of the fluorescent layer. The sensitivity of the arrangement (which is illustrated in FIG. 1) is:
E.sub.1 =KD.eta..sub.R..eta..sub.0, where PA1 D is the dose rate of the x-ray source, PA1 .eta..sub.R is the degree of x-ray efficiency, PA1 .eta..sub.0 is the degree of optical efficiency, and PA1 K is the conversion factor.
The conversion factor can be improved by mirror-coating the reverse (e.g. lower side) of the semiconductor diode or by double coating.